In an update to a controversial report, environmental activist group Greenpeace partly applauded Apple for taking more steps to add clean power to its data center, yet also said Apple should both be more transparent about its plans and should also be doing more.

Back in April Greenpeace slammed Apple, giving it failing marks in its ranking system, for not considering clean power enough when deciding where to locate its data centers (for more on clean power and data centers, read this detailed feature on the controversial world of clean power and data centers). In that report Greenpeace gave Google, Yahoo and Facebook higher marks than Apple.

Yet since that report came out, Apple has announced some major new clean power data center initiatives. Apple has recently said it will double the size of the solar farm at its data center in North Carolina (from 20 MW to 40 MW), and that the entire facility will eventually be run by 100 percent clean power. Apple has also said that its data center in Oregon will be run off of 100 percent clean power, and that all of its data centers will be coal-free by 2013.

Workers building out the power lines around Apple’s data center

On the face of it, Apple’s steps are huge news in the world of data center operators, which for a long time have not been willing to pay a premium for clean power. Instead, most data center builders seek out locations that have cheap (and often times coal-based) power — like North Carolina, which has a grid that runs largely off of coal and nuclear. North Carolina has been able to attract a cluster of some of the largest data centers in the world whose owners want to buy its cheap and reliable power.

But Greenpeace still says that Apple isn’t being transparent about how it will reach those clean power goals. Greenpeace didn’t raise Apple’s score on “transparency” at all, and it kept its “D” grade in the update to the report. Greenpeace did raise Apple’s score for “infrastructure siting” to a D (from an F), “energy efficiency and green house gas mitigation” to a C (from a D) and “renewable energy investment and advocacy” to a C (from a D). Apple has now basically “passed,” but still trails behind companies like Google and Facebook in the ranking system.

Greenpeace says it didn’t raise Apple’s scores more because Apple has not disclosed how it will power the rest of its data center in North Carolina (beyond the solar and fuel cell farms) with clean power considering the local utility has little clean power. Greenpeace says it looks like Apple will be buying Renewable Energy Credits to offset the rest of the power, which is a somewhat controversial practice.

Stay out! Of Apple’s solar farm

Greenpeace also says it’s unclear if Apple will be using the clean power from its solar and fuel cells farms onsite in North Carolina, or if it will be selling the power back to the utility Duke Energy and using the dirty grid energy instead to power the data center. Apple could earn money by selling the solar power and associated Renewable Energy Credits to Duke. It’s also not yet clear how Apple will reach its clean power goal in Oregon, as it hasn’t said which utility it will buy power from, says Greenpeace.

Part of the reason the original report back in April was controversial was because Greenpeace used an estimate for the power consumption of Apple’s data center in North Carolina that Apple says was way too high. While Greenpeace had estimated that Apple’s data center in North Carolina would consume 100 MW, Apple said it will only consume 20 MW. But in this latest report, Greenpeace still isn’t buying Apple’s figure as being transparent. Greenpeace revised its estimate that Apple’s data center in North Carolina will consume 81 MW.

Here’s a variety of things that Greenpeace wants Apple to do to improve its score:

1) Use its influence to push Duke Energy to add more clean power to its grid.

2) Choose a utility in Oregon for its data center that has a cleaner grid and not go with Pacific Power, which generates a lot of electricity from coal.

3) Use the clean power in North Carolina directly for the data center rather than selling it to Duke.

4) Use biogas, from a sustainable source, directly for its fuel cells in North Carolina.

5) Retire its energy credits from electricity generated in North Carolina. This is what energy service company PPL says about retiring RECs on its FAQ: “By retiring RECs using a certified REC tracking system, each REC may be issued and claimed only once. That way, you can be sure that the project owner selling the REC only did so once. In addition, as RECs are retired, new resources must be built to meet future renewable energy requirements.” Greenpeace says Apple could be counting its projects twice, which is a no-no in sustainability worlds.

6) Invest in more clean power for its facilities directly instead of potentially buying RECs to offset its fossil fuel use.

7) Adopt a clean power data center siting strategy.

For more on the mega data centers in North Carolina check out my four-part series this week: